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-   -   Big Sparks! (http://www.Wattflyer.com/forums/showthread.php?t=73507)

JetPlaneFlyer 04-06-2014 04:34 PM

Big Sparks!
 
Today i was hooking up one of my 6s batteries to the charger only half concentrating on what i was doing and I must have accidentally bridged between the + and - bullet connectors with the male bullet of the charging cable.

There was a big flash and this is what the 5.5mm bullets looked like a millisecond later:
http://i3.photobucket.com/albums/y65...120/sparks.jpg

The burned male (red) connector on the left is the charger cable, the two connectors on the right are the +/- off the battery, all are beefy 5.5mm bullets. the spark blew the end off one bullet and burned a hole straight through the side of the other!

Close up:
http://i3.photobucket.com/albums/y65...0/sparks_1.jpg

Luckily that was all the damage apart from a couple of tiny burns on my finger caused by flying molten metal (sounds worse than it was). Normally I keep a cap over the male (negative) battery terminal until I've connected the positive side up, but today I must have been daydreaming.. There's a lesson to be learned - Always concentrate when working with LiPos!!


This wasn't the only lesson though. I went about replacing the battery bullet connectors. These were original factory supplied connectors on the Turnigy LiPos.

Here's what the soldering socket of the male connector looked like:
http://i3.photobucket.com/albums/y65...0/sparks_2.jpg

Notable is the TOTAL lack of any solder in the socket:eek: All that was connecting the wire to the bullet was a thin fillet of solder between the side of the wire and the edge of the bullet, and that only ran around half the circumference. I shudder when I think I was pulling 140A through that connector.

So lesson number two - Re-solder every connector on your LiPos! (especially cheap ones)

xmech2k 04-06-2014 05:41 PM

Oops! Thanks for swallowing your pride and sharing that with us, and glad there wasn't any major injury or damage. A good lesson.

sidybee 04-06-2014 05:56 PM

i think they call that ark welding lol

CHELLIE 04-07-2014 12:40 AM

I hate that when that happens :( I have done that too :D It sure is a wake up Call :Q

Larry3215 04-07-2014 04:11 AM

Thats very scary seeing the lack of solder in that bullet!

I did almost exactly the same thing one time. I was charging at the field and one of the exposed male bullets touched the frame on my truck while connecting the charger.

I not only ruined the connector I shorted, but I also blew one of the aluminum tabs on one of the cells in the pack. It blew just like a fuse.

It took me a while to figure out why the pack read zero voltage after I soldered on a new connector! I knew it couldn't possibly have discharged down to zero that quickly.

Not paying attention can get expensive!

kyleservicetech 04-07-2014 05:26 AM

Quote:

Originally Posted by JetPlaneFlyer (Post 944701)

This wasn't the only lesson though. I went about replacing the battery bullet connectors. These were original factory supplied connectors on the Turnigy LiPos.
Notable is the TOTAL lack of any solder in the socket:eek: All that was connecting the wire to the bullet was a thin fillet of solder between the side of the wire and the edge of the bullet, and that only ran around half the circumference. I shudder when I think I was pulling 140A through that connector.

So lesson number two - Re-solder every connector on your LiPos! (especially cheap ones)

Yikes
140 Amps through that??? You're right, that was very fortunate to not have blown out in flight.


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